Foldline bellows

ABSTRACT

The foldline bellows consist of at least two mutually interposed systems of fold lines with a different ratio of the depth of the fold lines and with different thicknesses of individual parts of the walls of both systems. At maximum collapse some foldlines of both systems are staggered so that they require less space than ordinary bellows. They can be made of plastics and can have any arbitrary, for example, circular or square cross section and the form of a cylinder or a cone.

United States Patent Mazur Jan. 25, 1972 [54] FOLDLINE BELLOWS [72] Inventor: Jii Mazur, Prerov, Czechoslovakia [73] Assignee: Meopta Preror [22] Filed: July 27, 1970 [211 App]. No.: 58,589

Foreign Application Priority Data Aug. 8, 1969 Czechoslovakia ..PV55l2-69 [s2] Us. Cl ..95/39 [51] Int. Cl, ....G03b 17/04 [58] Field of Search ..95/39, 40

[56] References Cited v UNITED STATES PATENTS 2,578,111 12/1951 urner et a1.

FOREIGN PATENTS OR APPLICATIONS 71,772 11/1950 Denmark ..95/39 1,028,360 4/1958 Germany ..95/39 Primary Examiner-Joseph F. Peters Attorney-Richard Low and Murray Schaffer [57] ABSTRACT The foldline bellows consist of at least two mutually interposed systems of fold lines with a diflerent ratio of the depth of the foldvlines and with different thicknesses of individual parts of the walls of both systems. At maximum collapse some foldlines of both systems are staggered so that they require less space than ordinary bellows. They can be made of plastics and can have any arbitrary, for example, circular or square cross section and the form of a cylinder or a cone.

5 Claims, 3 Drawing Figures PAT-ENTEDmzsmzz INVENTOR Arm r mzug Y ATTRNEY FOLDLINE BELLOWS The invention relates to fold line bellows for the connection of two at least partly mutually axially moving mechanical parts, the bellows being made of one piece of yieldable material and particularly suitable for the connection of the negative carrier and the lens carrier of an enlarger.

Fold line bellows of this type are used for instance in photographic or reproduction apparatus for lighttight connection-of two mutually axially moving parts, usually of the lens carrier and the carrier of photosensitive material when applied in photographic cameras or of the negative carrier when applied in reproduction apparatus and, more particularly, enlargers.

In apparatus with exchangeable lenses it is desirable that the used fold line bellows allow to effect the largest possible relative displacement of both parts, while at the same time enabling their approach -at minimum distance. This minimum distance is usually limited by the inevitable thickness of the fold line bellows at its maximum collapse, i.e., at a position, where all'walls are folded along their respective fold lines into an essentially flat position. In fold line bellows hitherto used, this minimum distance is rather large, so that when applying an exchangeable lens with short focal distance in an enlarger designed for use with a basic lens with an essentially larger focal length, it is necessary to use a shaped adapter allowing insertion of the lens with small focal length into the intemalspace of the fold line bellows.

Well known are fold line bellows, used in pneumatic technics and having a circular cross section and a conical profile, their conicity being considerable so that the individual bendings, formed at the inner or outer edges do not meet at full collapse. In this case, at full collapse of the fold line bellows a relatively smaller minimum dimension is obtained.

It is however impossible to use fold line bellows of this type in opticomechanical devices of the above-mentioned type, since the dimensions of their upper and lower bases must be essentially different. Their possible use would mean that one of the carriers of the device would have to be extremely large, essentially larger than it would correspond to the requirements on the function of the device. I-Ierewith further drawbacks as e.g., enhancement of the dimensions and of the weight of the device are connected.

SUMMARY OF THE INVENTION The object of the invention is to provide such. a type of fold line bellows, which, while retaining the external dimensions hitherto used, would allow an essentially larger collapse than actually used fold line bellows without allowing the resistance at maximum collapse to be essentially increased.

The fold line bellows according to this invention have at least two mutually interposed systems of fold lines, created by adjacent bellow walls, each of both fold line systems having external and internal fold lines, either the external or internal fold lines of both fold line systems being created by bellow walls meeting at an acute angle, whereas the other fold lines of both systems are created by bellow walls forming a rounded edge, the bellow walls meeting at an acute angle to form fold lines having at their meeting place a greater thickness than bellow walls forming a rounded edge and adjacent fold lines of both interposed fold line systems created by bellow walls meeting at an acute angle are for the first fold line system at different distances from the longitudinal axis of the bellows than for the second fold line system.

DESCRIPTION OF THE DRAWINGS For a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed description taken in connection with the accompanying drawings wherein:

FIG. 1 is a schematic, fragmentary, enlarged sectional view of a portion of fold line bellows of cylindrical form FIG. 2 shows fully extended and fully collapsed fold line bellows according to FIG. 1, and

FIG. 3 is a schematic sectional view of fold line bellows of conical form.

DESCRIPTION OF PREFERRED EMBODIMENT Referring not to the drawings, in FIG. I is shown, in ensystems of fold lines, the first system I and the second system 2. The outer diameter 300 of both systems is equal, the first system 1 having a larger depth ll of the fold lines with inner edges l0andthe inner diameter 100.

The second system 2 has a smaller depth 21 of fold lines with inner edges 20 and an inner diameter 200. Bothsystems I and 2 have common outer edges 23 at the same level. The first system 1 has at the inner edge 10 a thickness 12 of the wall and on the inner diameter 200 of the second system 2, the first system I has athickness l3 of the wall. The second system 2 has at the inner edge 20a thickness 22 of the wall. Both systems have on the outer diameter 300 a thickness 24 of the wall. Thickness 12 of the wall is the largest, while thicknesses l3 and 22 ofthe corresponding walls are about one-half the thickness 12. The outer circumference of the inner edge 10 of the first system 1 of fold lines is sharp so that the corresponding edge forms a knife edge, while the inner circumference of this edge I0 is rounded. In the same way also the circumferences of the inner edge 20 of the second system 2 of fold lines are formed.

In FIG. 2 is schematically illustrated the cross section through fold line bellowsof cylindrical form. Corresponding dimensions are identical with those in FIG. 1. On both ends the fold line bellows are provided with end parts 14 following the dimensions of the first system 1 of the fold lines and allowing mechanical fastening of the fold line bellows, e.g., to the lens carrier and to the negative earlier when used in an enlarger. Inthe left half of FIG. 2 are shown fold line bellows in loose condition, occupying a loose length 30. The right half of FIG. 2, with respect to axis 5, shows the same fold line bellows in collapsed condition, when it occupies the least length 31.

FIG. 3 shows conical fold line bellows 4, again comprising two systems of fold line systems, namely the first system 6 and the second system 7 of fold lines. As obvious from FIG. 3 the first system 6 as well as the second system 7 consist of fold lines, whose diameter successively decreases so that the con- I necting lines 60, 61 and 71, 72 respectivelyof the corresponding outer and inner edges form an element of a ruled surface of a cone.

As obvious from the right half of FIG. 2 it is possible to collapse the fold line bellows without special strain force so that the individual inner edges 10 of the first system I touch each other. As the thicknesses 22, I3 of the walls of the fold lines of the individual systems are one-half the thickness 12 of the wall of system lat the.inner edge 10, also the sum of thicknesses of these walls is identical with the thickness of the walls at the above-mentioned inner edges 10. of the first system I. That means that at full collapse according to the right half of FIG. 2 the walls of the fold lines of both systems can become loosely adjacent so that the collapsed fold line bellows according to FIG. 2 really occupy the least possible, length. To an easy collapse also contributes the form of the outer circumference of inner edges 10 and 20 of the first. system 1 and of the second system 2 of fold lines.

In practical realization when applied in an enlarger it is for example possible to reach with bellows with eight fold lines, that is with four fold lines of the first system 1 with larger depth 11 and four fold lines of the second system 2 with smaller depth 21 in comparison with similar fold line bellows with fold lines of constant depth a difference of maximum collapse from 77 mm. to 7 mm. as compared with 13 mm. in bellows hitherto-used. These dimensions have been measured at the so-called loose collapse, which means that foe the collapse its construction from the standpoint of the profile of the individual systems of fold lines is identical with the previous construction according to H6. 1 and 2.

his obvious that the construction according to the invention is not limited to the described version only. So for example it is possible to make fold line bellows, where also the outer diameters of the individual systems of fold lines will be different, or where more than two systems of fold lines will be applied. Also the profile of the bellows need not be circular, it is possible to choose for instance a square profile and the like. It is equally possible to the external folding lines created by bellow walls meeting at an acute angle and the internal folding lines with rounded edges. Here it is fully possible to utilize the advantages of the technology of plastic moulding.

In practical embodiments, the ratio of depths of fold lines of both systems, that is the ratio of distances 1! of external and internal fold lines of one system to the distances 21 of corresponding fold lines of the second system is at least 3 to 2, advantageously but 2 to l. The thickness of bellow walls at the place where said walls are meeting at an acute angle to form folding lines is substantially greater for the first system with larger depth than for the second system with smaller depth, advantageously at least twice the thickness. The sum of thicknesses of bellow walls meeting at an acute angle to form fold lines is for the first fold line system with larger depth at mostidentical with the sum of thicknesses of bellow walls of both systems at a distance from the longitudinal axis of the bellows, corresponding to the distance of fold lines of the second fold line system with smaller depth, created by bellow walls meeting at an acute angle.

Fold line bellows according to this invention can be used with advantage for manufacture of optical apparatus, particularly of enlargers.

I claim:

1. Fold line bellows for the connection of two at least partly mutually axially movable mechanical parts, particularly for the connection of the negative carrier and the lens carrier of an enlarging apparatus comprising in combination: at least two mutually interposed systems of fold lines, created by adjacent walls of the bellows, each of said systems having external and internal fold lines with respect to the longitudinal axis of the bellows, the ratio of distances between external and internal fold lines of the first system to the distance of corresponding fold lines of the second system being at least 3 to 2, fold lines of said systems created alternately by bellow walls meeting at an acute angle and by bellow walls forming a rounded edge, bellow walls meeting at an acute angle to form a fold line having at this meeting place a greater thickness than bellow walls forming a rounded edge,

fold lines created by bellow walls meeting at an acute angle and fold lines created by bellow walls forming a rounded edge are for both fold line systems equally situated with respect to the longitudinal axis of the bellows,

adjacent fold lines of both interposed systems created by bellow walls meeting at an acute angle being for the first fold line system at different distances from the longitudinal axis of the bellows than for the second fold line system.

2. Fold line bellows as claimed in claim 1 with bellow walls meeting at an acute angle to form a fold line having for the first fold line system at their meeting place at least twice the thickness of walls than for the corresponding bellow walls of the second fold line system.

3. Fold line bellows as claimed in claim 1, the distance of external and internal folding lines of the first system with respect to corresponding folding lines of the second system being at a ratio of 2 to l, the distances of folding lines of both systems formed by rounded edges from the longitudinal axis of the bellows being equal and the sum of thicknesses of bellow walls meeting at an acute angle to form fold lines of the first fold line system being at most identical with the sum of thicknesses of bellow walls of both systems at a distance from the lon itudinal axis of the bellows, corresponding to the distance 0 fold 

1. Fold line bellows for the connection of two at least partly mutually axially movable mechanical parts, particularly for the connection of the negative carrier and the lens carrier of an enlarging apparatus comprising in combination: at least two mutually interposed systems of fold lines, created by adjacent walls of the bellows, each of said systems having external and internal fold lines with respect to the longitudinal axis of the bellows, the ratio of distances between external and internal fold lines of the first system to the distance of corresponding fold lines of the second system being at least 3 to 2, fold lines of said systems created alternately by bellow walls meeting at an acute angle and by bellow walls forming a rounded edge, bellow walls meeting at an acute angle to form a fold line having at this meeting place a greater thickness than bellow walls forming a rounded edge, fold lines created by bellow walls meeting at an acute angle and fold lines created by bellow walls forming a rounded edge are for both fold line systems equally situated with respect to the longitudinal axis of the bellows, adjacent fold lines of both interposed systems created by bellow walls meeting at an acute angle being for the first fold line system at different distances from the longitudinal axis of the bellows than for the second fold line system.
 2. Fold line bellows as claimed in claim 1 with bellow walls meeting at an acute angle to form a fold line having for the first fold line system at their meeting place at least twice the thickness of walls than for the corresponding bellow walls of the second fold line system.
 3. Fold line bellows as claimed in claim 1, the distance of external and internal folding lines of the first system with respect to corresponding folding lines of the second system being at a ratio of 2 to 1, the distances of folding lines of both systems formed by rounded edges from the longitudinal axis of the bellows being equal and the sum of thicknesses of bellow walls meeting at an acute angle to form fold lines of the first fold line system being at most identical with the sum of thicknesses of bellow walls of both systems at a distance from the longitudinal axis of the bellows, corresponding to the distance of fold lines of the second system, created by bellow walls meeting at an acute angle.
 4. Fold line bellows as claimed in claim 1, the fold lines created by bellow walls meeting at an acute angle terminating in a knife edge, whereas in the internal part the bellow walls pass over one into the other by way of a rounded place.
 5. Fold line bellows as claimed in claim 1 made of one piece of yieldable material, particularly of plastics. 